Multistage centrifugal pump adjustment mode

The working principle of multistage centrifugal pump is the same as that of ground centrifugal pump. When the impeller of the motor drives the shaft to rotate at high speed, the liquid filled in the impeller under the action of centrifugal force, from the center of the impeller along the runner between the blades to the impeller around, because the liquid is affected by the blade, the pressure and speed increase at the same time, through the guide housing runner and led to the next level of the impeller, so, Successive flows through all the impellers and guide housings further increase the pressure energy of the liquid.

What are the adjustment ways of multistage centrifugal pump? The two commonly used ways are introduced:

1. Throttle the valve

The simplest way to change the flow of the centrifugal pump is to adjust the opening of the pump outlet valve, and the multistage centrifugal pump speed remains unchanged (generally rated speed), its essence is to change the position of the characteristic curve of the pipeline to change the pump condition point. The intersection of pump characteristic curve Q-H and pipeline characteristic curve Q-∑h is the limit working condition point of the pump when the valve is fully opened. When the valve is closed, the local resistance of the pipeline increases, the working point of the pump moves to the left, and the corresponding flow decreases. When the valve is fully closed, the resistance is unlimited and the flow is zero. At this time, the characteristic curve of the pipeline coincides with the ordinate.

It can be seen that when the flow is controlled by closing the valve, the water supply capacity of the multistage centrifugal pump itself is unchanged, the head characteristics are unchanged, and the pipe resistance characteristics will change with the change of the valve opening. This method is easy to operate, continuous flow, can be adjusted between a relatively large flow and zero, and no additional investment, applicable to a wide range of occasions. But the throttle regulation is to consume the excess energy of the centrifugal pump to maintain a certain amount of supply, the efficiency of the centrifugal pump will also decline, the economy is not very reasonable.

2, frequency control

The basic condition for the pump speed regulation is that the operating point deviates from the high efficiency zone. When the speed of the multistage centrifugal pump changes, the valve opening remains unchanged (usually for relatively large opening), the piping system characteristics remain unchanged, and the water supply capacity and head characteristics change accordingly. In the case that the required flow is less than the rated flow, the head of frequency conversion speed regulation is smaller than the valve throttle, so the water supply power required for frequency conversion speed regulation is smaller than the valve throttle. Obviously, compared with the valve throttling, the energy-saving effect of frequency control is very prominent, the horizontal multistage centrifugal pump is more efficient.

In addition, the use of frequency control, not only is beneficial to reduce the possibility of centrifugal pump cavitation, but also can prolong the startup/shutdown process by the acceleration/deceleration time preset, so that the dynamic torque is greatly reduced, so as to eliminate the very destructive water hammer effect to a large extent, greatly prolonging the life of the pump and pipeline system.

Multistage centrifugal pump adopts the high efficiency and energy saving hydraulic model recommended by the state, which has the advantages of high efficiency and energy saving, wide range of performance, safe and stable operation, low noise, long life, easy installation and maintenance, etc. It is recommended to use the high efficiency and energy saving hydraulic model, which has the advantages of high efficiency and energy saving, wide performance range, safe and stable operation, low noise, long life, convenient installation and maintenance

Different multistage centrifugal pump manufacturers produce different multistage centrifugal pump models, multistage centrifugal pump is to have the same function of more than two pumps together, fluid channel structure, performance in the front of the medium pressure relief port and the second level of the inlet, the second level of the medium pressure relief port and the third level of the inlet, so the series of the formation of the multistage centrifugal pump. The significance of multistage centrifugal pump is to improve the set pressure.

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